Devoxx France: Bazel sample app

Sample app use for the Devoxx France 2019 conference "À la découverte de Bazel".

This "dummy" app is composed of multiple parts:

• gateway: a spring boot java app in the demo package
• fetcher: a scala app in the fetcher package
• domain: a java domain model in the domain package
• cache-server: a cache-server package use to build our remote cache server image

For managing external dependencies, I have both used (to show different tools):

• bazel-deps
• rules_jvm_external

Getting started

1. Install bazel by following the instructions from http://bazel.build
2. Retrieve and clone this repository

Build the project

Build and test with the version 0.24.1

Build and run binaries

Build and run the gateway binary:

bazel build :gateway
bazel run :gateway # env set to dev by default

or in a one shot:

bazel run :gateway # build and run it

Build and run the fetcher binary:

bazel run :fetcher

Test it

curl "http://localhost:3000/greet?name=Devoxx"

should return

{
  "data": "Hello Devoxx !",
  "from": "http://localhost:3000"
}

Add the remote cache

To perform our remote caching, we'll use an nginx server with the WebDAV module. We will run a container, and mount the container cache directory to an host volume. The container will expose the port number 8888.

Our nginx server will start with the following configuration:

events {
  worker_connections 1024;
}

http {
  sendfile on;
  server {

    location /cache/ {
      root /cache;
      dav_methods PUT;
      create_full_put_path on;
      client_max_body_size 1G;
      allow all;
    }

  }
}

Configure bazel to use the remote cache server

We could pass option directly with bazel CLI, or use a .bazelrc configuration file (this is what we are going to do).

Look at the .bazelrc file at the root repository, we've had this one:

build --remote_http_cache=http://0.0.0.0:8888/cache

Here, we're specifying which remote cache we should hit.

Build the cache-server (no need of docker)

bazel build :cache-server

Run the cache server (need to have a docker daemon)

bazel run :cache-server

Now, to test it, you can do:

bazel clean # clean our local cache

then build some stuff:

bazel build :gateway
bazel build :fetcher

We should see a lot of PUT request on our remote cache backend.

When all is built, clean the local cache by doing a bazel clean (simulate the fact that some other people populate our remote cache service).

then redo:

bazel build :gateway
bazel build :fetcher

We should see something like:

INFO: Elapsed time: 2.365s, Critical Path: 1.85s
INFO: 44 processes: 44 remote cache hit. # <- all actions are fetched from the remote cache \o/
INFO: Build completed successfully, 48 total actions